Aqueous fireproofing composition of sodium oxyfluoborate and phenol formaldehyde, method of treating paper therewith and article prepared therefrom



I :PAPERTHEREWITH 1 their preparation are claimed in U.

' also issued February 11, 1958. v 4 While the oxyfluoborates afford very good flameproofmg to cellulosic bases, they suffer from the disadvan- 5 tages of stifiening the material tocwhich they are apphenol-formaldehyde and the United States Pate 7 I 2,842,510 r AAQUEOUS FIREPROOFING COMPOSITION OF SODIUM OXYFLUOBORATE' AND V-FORMALDEHYDE, METHOD on TREATING AND ARTICLE PREPARED. THEREFROM e a: ilames A. Robertson, Lewiston, N. Y, assignor to E. I. du

Pont de Nemours and Company, Wilmington,'Del., a

corporation of Delaware 7 No Drawing. Application August 15,1955 Serial No. 528,561 7 Claims. (Cl. 260-293) This invention relates to flame resistant paper. i More particularly, it relates to such a manner that it is no stiffer than paper not .flamei resistant.

1 In US, Patent 2,823,145yiss'ue'd February 11, 1958, there is' revealed a new and excellent method of.fireproofing inflammable materials, cellulosic fibers in particular.

an oxyfluoborate of the formula NaF-xB O where x varies between about 1.17 and 1.45, 'or a hydrate there- A of. Especially valuable is the compound NaF-1.25B 'O V audits hydrates.

This method consists in supplying to the fibers These compounds and methods, for S. Patent 2,823,095,

PHENOL mately desired in the paper. This percentage is generally between about 5 and 15% by weight; Since there is no preferential absorption with the oxyfluoborates, or with any other material used in the present solution, the percentage of compound I that there is 100% absorption from solution.

paper made flame-resistantin containing thermosetting monomers has thus, heretofore, 3

been somewhat inconvenient.

j object of this invention is, consequently, provision of paper or other fibrous articles containing 'both oxyfluoborates and the uncured form of thermosetting resins, phenol-formaldehyde in I stiff to be bent readily.

Another object is provision of a method'for supplying both oxyfluoborates and thermosetting resins to apaper base without stiffening the base excessively when the latter'is dried. W

The above-mentioned and still further objects are I j achieved in accordance with this invention by impregnating inflammable bases, paper in particular, from an aque ous solutioncontainingthe uncured form of the thermosetting resin, an oxyfluoborate and also a plasticizer of i the group consisting of water-soluble polyhyclric alcohols 'and'water-soluble polyethylene glycols. These plasticizing agents are not'operative to soften paper impregnated with oxyfluoborates alone. Their effect-in: their present ,u'sageis' thus quite surprising. i

The oxyfluoborates of the impregnating-solution are, of course, those of U. 8. Patent 2,823,145. 'A preferred composition is 4NaF-5B O or the hydrate ,The quantity of oxyfluoborate dissolved is determined basically by the percentage of flameproofing agent ultiparticular; which .are not too 7 bowax.

' tered in commerce.

11-13% by weight is generally The preferred thermosetting resin for use in the paper of this invention is. phenohfor'maldehyde. Consequently, the precursor of this material, A stage phenol-formaldehyde, is also included in the impregnating solution.

The quantity of this material dissolved is also determined paper product. About used in the paper .but' To insure that'the' ultimately by that needed in the smaller quantities are acceptable. desired quantity is absorbed from 15 stage material. Between about 5 and 15% by weight the solution, about is usually satisfactory and will deposit roughly about -15 by weight of the paper on the paperwhenthe latter is wetted with its own weight of solution. j Other phenol-formaldehyde may These include urea-form-i aldehyde, melamine-formaldehyde and the, like. The

thermosetting resins besides be employed in this process;

quantity of 'these .materials necessary is roughly .equivalent to that of phenol formaldehyde, both in solution in the A stage form and on the papenultinrateli as the polymer.

' The preferred polyhydric alcohols for use'to soften paper impregnated with the organic monomers and oxy;

fluoborate are glycerine and ethylene glycol but others may be used as well. The quantity employed will vary with the combined weight of flameproofing agentand monomers and, in the case if glycerine, may comprise up to about 15% by weight of this'weightr About.5%

is preferred, based upon the weight. of oxyfluoborate V hydrate either in solution or on the dried paper. Above 5% can be used but the higher percentages yield nocom mensurate gains and hence are not desired. 7

The water-soluble polyethylene glycols having 'rnolecular weights between about 200 and 20,000 are suitvable for the purposes of the invention. A molecular weight of about 1500 gives the'bestresults. The quantity of these polyglycols required that. of the polyhydric alcohols;

fiuoborates, is preferred.

Polyethylene glycols are conveniently supplied to the: impregnating solution as Carbowax. This is the trade name of glycols sold by the Carbide and Carbon Chem-. icals Corporation and is defined in the Handbook of Material Trade Names, Zimmerman and Lavine,.Industrial Research Service (1953). The molecular weight of thepolyglycol is determined by the number afiixed to Car- Thus Carbowax 1500 has a molecular weight of 1500. .f

'One factor which influences to some extent the chosen concentration of all ag'entsin the solution is the contact time between it andthe untreated paperrfThe vala ues given are effective for about the minimum time required for thorough wetting of paper normally encoun At thorough wetting thepaper absorbs about of its weight of solution,f When the water is evaporated, the percentageof solid deposited will be slightly less than the percentage in solution.

Thorough wetting occurs in a matter of secondspfor ordinary paper being essentially the time requiredto dip the paper slowly into solution and remove it. Greater solution concentrations may be employed ifvvery rapid 1 e dips are required. Adjustment of solution concentration 2.842.516 Patented JuljS, s.

(hydrate) in solution should be about the same, i; e., 5-15 by weights- This state-. ment is based. on the approximately correct assumption by weight of the solution should consist of theA is about the same, as; Thus betweeuabout 5 and 15 by weight, based on the weight of the oxya and contact time to obtain a particular concentration of solids on the paper is, in any case, very simple where there is no preferential absorption. Room temperature, i. e., 20-2S C., is effective for this contact but higher temperatures may be employed.

The composition of the aqueous impregnating solutions may now be summarized. To obtain a flame-resistant paper soft'enough for convenient manipulation but containing sufficient A stage material for ultimate strength, the aqueous solution may comprise about l5% by weight of the oxyfiuoborate hydrate, about 5l5% by weight of phenol-formaldedyde, and 05-15% by weight of glycerine or other Water-soluble polyhydric alcohol. Such a solution will yield a dried paper containing about 515% of the flame-resistant agent, about 545% of the thermosetting material and 0.51.5% of the plasticizer, again assuming 100% absorption from solution. When the polyethylene glycols are substituted for the polyhydric alcohols, about 05-15% of the former is included in solution to yield a paper containing the same quantity of plasticizer.

The process may also be summarized. Paper is dipped into a solution of one of the compositions given above at room temperature for about the minimal time complete wetting. The paper is then removed and dried as convenient. It will be understood that the drying temperature is less than that needed to set the resin. The steps enumerated so far are those of a primary manufac turer and yield an intermediate product to be operated upon by secondary manufacturers. The steps taken by the latter are (1) forming the basic paper product into any desired shape and (2) heating the shape to cure the thermosetting resin. These final steps yield a product retaining its shape indefinitely.

Stifiness" or softness as used in this application is not qualitative. it can, on the contrary, be measured quantitatively as on a Tinius-Olsen stifiness tester. This is an instrument sold by the Tinius-Olsen Company of Philadelphia, Pennsylvania. Results are expressed in arbitrary units proportional to the resistant force exerted by the paper or other material as it is twisted through various angles.

There follow some examples which illustrate the invention in detail. In these examples all percentages are TABLE Stiflness of impregnated paper (air dried) Solids 1 Resistance Force Ex- Impregnant Wt. Ratio oln Dry aper ample 14. 0 23. 5 27. 3 13.1 15. 6 31. 0 39. 0 13. 6 6.8 12.0 14. 8 1:1 13.1 11.0 20. 3 26.1 1:0. 05 13. 4 16. 2 32.3 30. 8 1:1:0. 1 13. 2 8.0 14.0 17.8 1:1:0. 3 14. 5 7. 5 13. 7 17.0 1:1:0. 02 13. 7 12. 3 23.0 28. 0 1:1:0. 04 14.1 8. 3 16.0 20. 0 1:1:0. 06 14.4 8.3 14. 7 18. 5 121:0. 08 14.1 8.5 15. 3 18. 5 1:1:0. 1 12. 8 12.0 22. 8 29. 8 1:1:0.3 13.4 7.8 13.3 17.3 1:110. 1 12.1 7. 8 14. 5 10. 1:1:0.3 13.8 8. 0 15.0 18. 8 1:1:0. 1 12. 7 3. 2 16. 8 19. 3 '1:1:0.3 16.5 9.3 16.2 19.8 PF+OFB+G20.. 1:1:0. 1 12.8 10. 5 18. 7 23. 2 PF+OFB+O20. 121:0.3 14. 6 7. 3 13.8 11. 5

1 Absorption from solutions was somewhat less than 100%. The percentage of dissolved material in the impregnating solution was 18%.

given in terms of weight. Stifiness tests were made at room temperature on the Tinius-Olscn tester mentioned above.

A series of experiments was carried out in which ordinary heavy kra'ft Wrapping paper was dipped at room temperature into solutions containing various impregnants, dried andtested for stiffness. Results and other pertinent data are given in the table. In the'table OFB is 4NaF-5B O -5H O, PF is phenol-formaldehyde in the men A-stage form, G is glycerine, C2 is Carbo- 200, C3 is Carbowax 1500, C6 is Carbowax 6,000 and C20 is Carbowax 20,000.

Having described my invention, 1 claim:

1. An aqeous solution for fireproofing paper and other fibrous articles which comprises about 5-l5% by weight '1 sodium oxyfiuoborate hydrate, about 515% by weight of A stage phenol-formaldehyde and about 0.5- '57 by weight of a water-soluble softening agent of the group consisting of glycerine, ethylene glycol, and pol ethylene glycols having a molecular weight between about 200 and 20,000.

2. An aqueous solution for flameproofing paper and other fibrous articles which comprises about 5-15% by weight of sodium oxyfiuoborate hydrate, about 515% by weight of A stage phenol-formaldehyde and about 0.5 1.5% by weight of glyceriue.

3. An aqueous solution for fiameproofing paper and other fibrous articles which comprises about 5-15% by weight of sodium oxyfluoborate hydrate, about 515% by weight of A stage phenol-formaldehyde and about 0.5- 1.5% by weight of a water-soluble polyethylene glycol having a molecular weight between about 200 and 20,000.

4. The method of producing paper which is soft and yet fireproofed by means or" sodium oxyfiuoborate which comprises immersing the paper to be treated for a short time in an aqueous solution comprising about 515% by weight of sodium oxyfiuoborate hydrate, about 5-15 by weight of A stage phenol-formaldehyde and about 0.51.5% by weight of a water-soluble softening agent or the group consisting of glycerine, ethylene glycol, and polyethylene glycols having a molecular Weight between about 200 and 20,000, and subsequently drying the treated paper at a temperature less than that required to set the resin.

5. The article produced by the method of claim 4.

6. The method of producing a fireproofed, shaped article which comprises immersing paper for a short time in an aqueous solution comprising about 5-15 by weight of sodium oxyfiuoborate hydrate, about 545% by weight of A stage phenol-formaldehyde and about 05-15% by weight of a water-soluble softening agent of the group consisting of glycerine, ethylene glycol, and

polyethylene glycols having a molecular weight between about 200 and 20,000, drying the treated paper, forming the paper into the desired shape and heat-curing the shape to produce thermoset phenol-formaldehyde, and thereby permanently setting the shape in the paper.

7. The article produced by the method of claim 6.

itefereritces Cited in the file of this patent UNITED STATES PATENTS 1954), edition 8014b. 

1. AN AQUEOUS SOLUTION FOR FIREPROOFING PAPER AND OTHER FIBROUS ARTICLES WHICH COMPRISES ABOUT 5-15% BY WEIGHT OF SODIUM OXYFLUOBORATE HYDRATE, ABOUT 5-15% BY WEIGHT OF A STAGE PHENOL-FORMALDEHYDE AND ABOUT 0.51.5% BY WEIGHT OF A WATER-SOLUBLE SOFTENING AGENT OF THE GROUP CONSITING OF GLYCERINE, ETHYLENE GLYCOL, AND POLYETHYLENE GLYCOLS HAVING A MOLECULAR WEIGHT BETWEEN ABOUT 200 AND 20,000. 